The present invention relates generally to rocket propulsion systems, and more specifically to a high temperature composite polar boss for use in place of metal for rocket motor polar bosses.
Development and production for solid rocket motors can be seriously affected by the long acquisition lead times for the conventional forged metal polar bosses used in composite motor cases. In addition, the long lead times for forged tooling severely restrict needed development program flexibility in making design changes. As an example, the development program for the inertial upper stage (IUS) solid rocket motors, had lead times of over a year for the closed-die forgings.
The task of finding an alternative to metal for rocket motor polar bosses, particularly for rockets with high operating temperatures is alleviated, to some extent, by the systems disclosed in the following U.S. patents, the disclosures of which are incorporated by reference:
U.S. Pat. No. 4,745,008 issued to Plotzker et al; PA1 U.S. Pat. No. 3,465,965 issued to Schrewelius; PA1 U.S. Pat. No. 4,359,190 issued to Pagano; PA1 U.S. Pat. No. 4,369,894 issued to Grover et al; PA1 U.S. Pat. No. 4,501,841 issued to Herring; PA1 U.S. Pat. No. 4,504,532 issued to Herring, and PA1 U.S. Pat. No. 4,523,524 issued to Cobb.
Cobb shows a solid propellant rocket motor tube or casing made of composite material such as graphite or glass fibers bonded together. A nozzle is attached to the aft end of the tube by bolt and nut.
Grover et al are concerned with a filament would pressure vessel having a polar opening with a fitting disposed in the opening and protruding therefrom. A plurality of layers of filaments are wound about the polar fitting.
Pagano discusses a rocket nozzle formed by laminating identical fabric-reinforced composite plies of uniform thickness in such a way that each ply extends to the extremities of the body in both the radial and axial directions. Claim 7 of this patent mentions a matrix of graphite cloth reinforced with phenolic, and in which the matrix is impregnated with a pitch-furfural blend, carbonized, and graphitized.
Schrewelius is directed to a tail-pipe nozzle for rocket motors having at least on the inside a fine-mesh, and a three-dimensional skeleton of recrystallozed silicon carbide. The two Herring patents both disclose temperature resistant heat insulator materials for rocket motors. Carbon fibers are mentioned as one of the materials in Herring Patent No. 4,504,532.
Since the introduction of carbon-carbon materials into solid rocket motor nozzles, the number of parts making up the nozzle has decreased dramatically, resulting in a much simpler structure. The above-cited Plotzker et al reference discloses a process for fabricating carbon-carbon articles. However, while the above-cited references are instructive, the need remains to provide an alternative to metal for the polar bosses of rocket motors with high operating temperature. The present invention is intended to satisfy that need.